Image sensor and imaging device

ABSTRACT

A first pixel comprises a first transfer transistor, a first reset transistor, a first amplifier transistor and a first select transistor. The first transfer transistor has a first terminal coupled to a reference signal generation circuit. The first reset transistor has a first terminal coupled to the reference signal generation circuit. The first amplifier transistor has a gate coupled to a second terminal of the first reset transistor and a second terminal of the first transfer transistor. The first select transistor is coupled to the first amplifier transistor. A second pixel comprises a first photoelectric conversion element, a second transfer transistor coupled to the first photoelectric conversion element, a second reset transistor configured to receive a first predetermined voltage, a second amplifier transistor coupled to the second transfer transistor and the second reset transistor, and a second select transistor coupled to the second amplifier transistor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 371 as a U.S.National Stage Entry of International Application No. PCT/JP2017/037371,filed in the Japanese Patent Office as a Receiving Office on Oct. 16,2017, which claims priority to Japanese Patent Application NumberJP2016-233875, filed in the Japanese Patent Office on Dec. 1, 2016, eachof which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present technology relates to an imaging device, and moreparticularly, to an imaging device operable to detect a failure ofthemselves.

BACKGROUND ART

In the related art, a test pixel is employed to detect a failure ofitself in an image sensor having a pixel array unit formed by arrangingpixels in a matrix shape. For example, an image sensor has beenproposed, in which a test for an analog/digital (A/D) converter thatconverts an image signal output from the pixel array unit into a digitalsignal is performed by inputting a test voltage generated by the testpixel to the A/D converter (For example, see Patent Literature 1). Inthis image sensor, the functional test of the A/D converter is performedby generating different test voltages from each test pixel arranged ineach row and performing analog/digital conversion for the test voltages.

CITATION LIST Patent Literature

PTL 1: U.S. Pat. No. 8,823,850

SUMMARY Technical Problem

In the related art described above, linearity of the A/D converter orthe like is tested by comparing a signal subjected to the analog/digitalconversion and the test voltage. For this reason, in a case where anabnormal signal is detected during the test, it is difficult todetermine which one of the A/D converter or a signal line that transmitsa control signal to pixels of the pixel array unit causes an error anddetect a failure such as disconnection of the signal line.

The present technology was made in view of the aforementionedcircumstances, and it is desirable to detect a failure in a signal linethat transmits a control signal to pixels of an image sensor.

Solution to Problem

The present technology was made to deal with the aforementionedcircumstances, and a first aspect of the present technology is an imagesensor including: An imaging device comprising: a first pixelcomprising: a first transfer transistor, wherein a first terminal of thefirst transfer transistor is coupled to a reference signal generationcircuit; a first reset transistor, wherein a first terminal of the firstreset transistor is coupled to the reference signal generation circuit;a first amplifier transistor, wherein a gate of the first amplifiertransistor is coupled to a second terminal of the first reset transistorand a second terminal of the first transfer transistor; and a firstselect transistor coupled to the first amplifier transistor; and asecond pixel comprising: a first photoelectric conversion element; asecond transfer transistor coupled to the first photoelectric conversionelement; a second reset transistor configured to receive a firstpredetermined voltage; a second amplifier transistor coupled to thesecond transfer transistor and the second reset transistor; and a secondselect transistor coupled to the second amplifier transistor.

Further, in the first aspect, the test voltage generator may change thetest voltage supplied to the test signal generator when the transfertest signal is generated from the transfer test voltage to a voltagedifferent from the transfer test voltage. As a result, it is possible tochange the test voltage when the transfer test voltage is generated.

Further, in the first aspect, the failure detector may detect a failureof the transfer control signal line in a case where the transfer testsignal has a voltage different from the transfer test voltage. As aresult, it is possible to detect a failure in the transfer controlsignal line in a case where the transfer test signal and the transfertest voltage have different voltages.

Further, in the first aspect, the failure detector may detect a failureof the transfer control signal line in a case where the reset testsignal has a voltage different from the reset test voltage. As a result,it is possible to detect a failure in the transfer control signal linein a case where the reset test signal and the reset test voltage aredifferent.

Further, in the first aspect, the failure detector may detect a failureof the reset control signal line in a case where the reset test signalhas a voltage different from the reset test voltage. As a result, it ispossible to detect a failure in the reset control signal line in a casewhere the reset test signal and the reset test voltage are different.

Further, in the first aspect, the test voltage generator may supply, asthe transfer test voltage, a reset voltage which is a voltage applied tothe electric charge storing element in the event of the reset operation.As a result, it is possible to supply the reset voltage as the transfertest voltage.

Further, in the first aspect, the test voltage generator may supply, asthe reset test voltage, a voltage ranging within a dynamic range of animage signal depending on the electric charges stored in the electriccharge storing element. As a result, it is possible to supply a voltageranging within a dynamic range of the image signal as the reset testvoltage.

Further, in the first aspect, the electric charge storing element may bearranged in a pixel, and an image signal depending on the electriccharges stored in the electric charge storing element may be generatedfrom the pixel. As a result, it is possible to generate an image signaldepending on electric charges of the electric charge storing elementarranged in the pixel.

Further, in the first aspect, the test signal generator may have acapacitor configured to store the test voltage, a signal generationelement configured to generate an error signal depending on the testvoltage stored in the capacitor, a transfer test signal generatorconfigured to apply the test voltage to the capacitor in response to thetransfer control signal to allow the signal generation element togenerate the transfer test signal, and a reset control signal generatorconfigured to apply the test voltage to the capacitor in response to thereset control signal to allow the signal generation element to generatethe reset test signal. As a result, it is possible to generate thetransfer test signal and the reset test signal depending on the testvoltage stored in the capacitor.

Further, in the first aspect, the image sensor may further include apixel selection control signal line configured to transmit, to thepixel, a pixel selection control signal that controls output of thegenerated image signal from the pixel, in which the test signalgenerator may output the transfer test signal and the reset test signalin response to the transmitted pixel selection control signal, and thefailure detector may further detect a failure of the pixel selectioncontrol signal line on the basis of the output transfer test signal andthe output reset test signal. As a result, it is possible to detect afailure in the pixel selection control signal line on the basis of thetransfer test signal and the reset test signal.

Further, in the first aspect, the failure detector may detect a failureof the pixel selection control signal line in a case where the transfertest signal has a voltage different from the transfer test voltage. As aresult, it is possible to detect a failure in the pixel selectioncontrol signal line in a case where the transfer test signal and thetransfer test voltage are different.

Further, in the first aspect, the failure detector may detect a failureof the pixel selection control signal line in a case where the resettest signal has a voltage different from the reset test voltage. As aresult, it is possible to detect a failure in the pixel selectioncontrol signal line in a case where the reset test signal and the resettest voltage are different.

Further, in the first aspect, the image sensor may further include acontrol signal generator configured to generate the transfer controlsignal and the reset control signal and transmit the transfer controlsignal and the reset control signal through the transfer control signalline and the reset control signal line, respectively. As a result, it ispossible to generate the transfer control signal and the reset controlsignal using the control signal generator.

Further, in the first aspect, the transfer control signal line may havea signal line commonly connected to the control signal generator, thepixel, and the test signal generator in this order, and the resetcontrol signal line may have a signal line commonly connected to thecontrol signal generator, the pixel, and the test signal generator inthis order. As a result, it is possible to arrange the test signalgenerators in end elements of the transfer control signal line and thereset control signal line.

Further, in the first aspect, the image sensor may further include: asecond control signal generator configured to generate the transfercontrol signal and the reset control signal; and a second test signalgenerator configured to generate the transfer test signal and the resettest signal, in which the transfer control signal line may have a signalline commonly connected to the control signal generator, the test signalgenerator, the pixel, the second test signal generator, and the secondcontrol signal generator in this order, and the reset control signalline may have a signal line commonly connected to the control signalgenerator, the test signal generator, the pixel, the second test signalgenerator, and the second control signal generator in this order. As aresult, it is possible to arrange the test signal generators in both endelements of the transfer control signal line and the reset controlsignal line.

Further, in the first aspect, the pixels may be arranged in a matrixshape, the test signal generator may be arranged in each row, thetransfer control signal line may be arranged each row to transmit thetransfer control signal to the pixel and the test signal generator, thereset control signal line may be arranged in each row to transmit thereset control signal to the pixel and the test signal generator, and thefailure detector may detect a failure in a plurality of the transfercontrol signal lines and a plurality of the reset control signal lineson the basis of the transfer test signal output from a plurality of thetest signal generators and the reset test signal output from a pluralityof the test signal generators. As a result, it is possible to detect afailure in the transfer control signal line and the reset control signalline arranged in each row using the test signal generated from the testsignal generators arranged in each row.

Further, in the first aspect, the image sensor may further include afailure information generator configured to generate failure informationas information on the failed row in which at least one of the transfercontrol signal lines and the reset control signal lines is failed on thebasis of a result of the detection of the failure detector. As a result,it is possible to create information on a failed row as the failureinformation.

Further, in the first aspect, the image sensor may further include acorrection unit configured to correct the output image signal on thebasis of the generated failure information. As a result, it is possibleto correct the image signal of the failed row.

Further, in the first aspect, the control signal generator may be formedin a semiconductor chip different from that in which the pixel and thetest signal generator are formed, the transfer control signal line maytransmit the transfer control signal between the different semiconductorchips through a connection terminal, and the reset control signal linemay transmit the reset control signal between the differentsemiconductor chips through a connection terminal. As a result, it ispossible to transmit the transfer control signal and the reset controlsignal through the connection terminal arranged between differentsemiconductor chips.

Further, a second aspect of the present technology is an imaging deviceincluding: an electric charge storing element configured to store atransferred electric charge; a transfer control signal line configuredto transmit a transfer control signal that controls a transfer of theelectric charges generated in response to emitted light to the electriccharge storing element; a reset control signal line configured totransmit, to the pixel, a reset control signal that controls a resetoperation of the electric charge stored in the electric charge storingelement; a test signal generator configured to generate a transfer testsignal on the basis of a test voltage for detecting a failure in thetransfer control signal line and the reset control signal line and thetransmitted transfer control signal and generate a reset test signal onthe basis of the test voltage and the transmitted reset control signal;a test voltage generator configured to supply a transfer test voltage tothe test signal generator as the test voltage when the transfer testsignal is generated and supply a reset test voltage to the test signalgenerator as the test voltage when the reset test signal is generated; afailure detector configured to detect a failure in the transfer controlsignal line and the reset control signal line on the basis of thegenerated transfer test signal and the generated reset test signal; anda processing circuit configured to process an image signal generateddepending on the electric charge stored in the electric charge storingelement. As a result, it is possible to supply different test voltageswhen the transfer test signal is generated and when the reset testsignal is generated.

According to an embodiment of the present technology, it is possible todetect a failure in the signal line that transmits the control signal tothe pixels of the image sensor. Note that the effects of the presenttechnology are not necessarily limited to those described herein, butmay include anything of this disclosure. [Advantageous Effects ofInvention]

According to an embodiment of the present technology, it is possible todetect a failure in the signal line that transmits the control signal tothe pixels of the image sensor. Note that the effects of the presenttechnology are not necessarily limited to those described herein, butmay include anything of this disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an exemplary configuration of animaging device 1 according to a first embodiment of the presenttechnology.

FIG. 2 is a diagram illustrating an exemplary configuration of a pixel110 according to the first embodiment of the present technology.

FIG. 3 is a diagram illustrating an exemplary configuration of a testsignal generator 120 according to the first embodiment of the presenttechnology.

FIG. 4 is a diagram illustrating an exemplary configuration of avertical scanning unit 210 according to an embodiment of the presenttechnology.

FIG. 5 is a diagram illustrating an exemplary configuration of an A/Dconversion unit 230 according to the first embodiment of the presenttechnology.

FIG. 6 is a diagram illustrating an exemplary configuration of an A/Dconversion element 231 according to an embodiment of the presenttechnology.

FIG. 7 is a diagram illustrating an exemplary configuration of a failuredetector 280 according to the first embodiment of the presenttechnology.

FIG. 8 is a diagram illustrating exemplary configurations of a pixelarray unit 10 and a driving unit 20 according to an embodiment of thepresent technology.

FIG. 9 is a diagram illustrating an exemplary configuration of aconnection terminal 160 according to an embodiment of the presenttechnology.

FIG. 10 is a diagram illustrating another exemplary configuration of theconnection terminal 160 according to an embodiment of the presenttechnology.

FIG. 11 is a diagram illustrating an example in which an image signaland a test signal are generated according to an embodiment of thepresent technology.

FIG. 12 is a diagram illustrating an example of the test signal when atransfer control signal line is failed according to an embodiment of thepresent technology.

FIG. 13 is a diagram illustrating an example of the test signal when areset control signal line is failed according to an embodiment of thepresent technology.

FIG. 14 is a diagram illustrating an example of the test signal when apixel selection control signal line is failed according to an embodimentof the present technology.

FIG. 15 is a diagram illustrating another example of the test signalwhen the pixel selection control signal line is failed according to anembodiment of the present technology.

FIG. 16 is a diagram illustrating an exemplary configuration of animaging device 1 according to a second embodiment of the presenttechnology.

FIG. 17 is a diagram illustrating an exemplary configuration of animaging device 1 according to a third embodiment of the presenttechnology.

FIG. 18 is a diagram illustrating an exemplary configuration of a pixelunit 410 according to the third embodiment of the present technology.

FIG. 19 is a diagram illustrating an exemplary configuration of afailure detection unit 420 according to the third embodiment of thepresent technology.

FIG. 20 is a diagram illustrating an exemplary configuration of an A/Dconversion unit 230 according to the third embodiment of the presenttechnology.

FIG. 21 is a diagram illustrating an exemplary configuration of animaging device 1 according to a fourth embodiment of the presenttechnology.

FIG. 22 is a diagram illustrating an exemplary configuration of afailure detector 280 according to the fourth embodiment of the presenttechnology.

FIG. 23 is a diagram illustrating an exemplary configuration of animaging device 1 according to a fifth embodiment of the presenttechnology.

FIG. 24 is a diagram illustrating an exemplary configuration of a pixelarray unit 10 according to a sixth embodiment of the present technology.

FIG. 25 is a diagram illustrating an exemplary configuration of afailure detector 280 according to the sixth embodiment of the presenttechnology.

FIG. 26 is a diagram illustrating an exemplary configuration of a pixel110 according to a seventh embodiment of the present technology.

FIG. 27 is a block diagram schematically illustrating an exemplaryconfiguration of a vehicle control system.

FIG. 28 is an explanatory diagram illustrating an exemplary installationposition of an image sensing unit.

DESCRIPTION OF EMBODIMENTS

Examples for embodying the present technology (hereinafter, referred toas “embodiments”) will now be described. The description will be made inthe following sequence.

1. First Embodiment (in a case where an image sensor includes aplurality of semiconductor chips)

2. Second Embodiment (in a case where an image sensor includes a singlesemiconductor chip)

3. Third Embodiment (in a case where a pixel array unit includes aplurality of pixel units)

4. Fourth Embodiment (in a case where analog/digital conversion of atest signal is omitted)

5. Fifth Embodiment (in a case where an image signal of a failed row iscorrected)

6. Sixth Embodiment (in a case where a test voltage is generated foreach row)

7. Seventh Embodiment (in a case where a failure of the signal line isdetected from a pixel)

1. First Embodiment Configuration of Imaging Device

FIG. 1 is a diagram illustrating an exemplary configuration of theimaging device 1 according to the first embodiment of the presenttechnology. The imaging device 1 includes a pixel array unit 10 and adriving unit 20. In addition, the driving unit 20 includes a verticalscanning unit #1 (210), a vertical scanning unit #2 (220), an A/Dconversion unit 230, a test voltage generator 240, a reference signalgenerator 250, a control unit 260, a signal processing unit 270, and afailure detector 280.

The pixel array unit 10 is configured by arranging pixels 110 thatgenerate image signals in response to emitted light in a matrix shape.In addition, a signal line 21 as a signal line that transmits a controlsignal to the pixels 110 is arranged in each row of the pixel array unit10 and is wired commonly between the pixels 110 arranged in each row. Asdescribed below, the signal line 21 includes a transfer control signalline that transmits a transfer control signal, a reset control signalline that transmits a reset control signal, and a pixel selectioncontrol signal line that controls image signals output from the pixels110. In addition, a signal line 11 for transmitting the image signalsgenerated from the pixels 110 is arranged in each column of the pixelarray unit 10 and is wired commonly between the pixels 110 arranged ineach column.

In addition, test signal generators 120 and 130 that generate testsignals for detecting a failure of the signal line 21 are arranged ineach row of the pixel array unit 10. The test signal generators 120 and130 are arranged in both ends of each row, and the signal lines 11 and21 are wired in a similar manner to that of the pixels 110. In addition,a signal line 22 that transmits the test voltage is further wired to thetest signal generators 120 and 130. Here, the test voltage refers to asignal for detecting a failure in the transfer control signal line andthe reset control signal line described above. The test signalgenerators 120 and 130 generate a transfer test signal and a reset testsignal as the test signals. The transfer test signal is generated on thebasis of the test voltage and the transfer control signal, and the resettest signal is generated on the basis of the test voltage and the resetcontrol signal. Configurations of the pixels 110, the test signalgenerator 120, and the like will be described below in more details.Note that the test signal generator 130 is an example of a second testsignal generator described in the claims.

A vertical scanning unit #1 (210) and a vertical scanning unit #2 (220)generate control signals for the pixels 110 and output the controlsignals through the signal line 21. The vertical scanning units #1 (210)and #2 (220) generate the transfer control signal, the reset controlsignal, and the pixel selection control signal described above as thecontrol signals. In addition, the vertical scanning units #1 (210) and#2 (220) generate the same control signal and output it to the signalline 21 at the same time in order to provide redundancy in generation ofthe control signal. Configurations of the vertical scanning units #1(210) and #2 (220) will be described below in more details. Note thatthe vertical scanning unit #1 (210) is an example of a control signalgenerator described in the claims. The vertical scanning unit #2 (220)is an example of a second control signal generator described in theclaims.

The A/D conversion unit 230 converts an image signal generated from thepixel 110 into a digital image signal. The A/D conversion unit 230 hasA/D conversion elements 231 arranged in each column of the pixel arrayunit 10 to perform analog/digital conversion, and a signal line 11 iswired to each A/D conversion element 231. In addition, the A/Dconversion unit 230 further has an A/D conversion element 231 arrangedto perform analog/digital conversion for a test signal generated fromthe test signal generators 120 or the like. The digital image signalgenerated through the analog/digital conversion is output to the signalprocessing unit 270. Meanwhile, the digital test signal is output to thefailure detector 280. The configuration of the A/D conversion unit 230will be described below in more details.

The test voltage generator 240 generates a test voltage and outputs thetest voltage to the test signal generators 120 and 130 through a signalline 22. The test voltage generator 240 generates a transfer testvoltage and a reset test voltage as the test voltage. The transfer testvoltage and the reset test voltage are test voltages having differentvoltages. The transfer test voltage is a test voltage generated when thetransfer test signal is generated by the test signal generators 120 orthe like. The reset test voltage is a test voltage generated when thereset test signal is generated by the test signal generators 120 or thelike. The test voltage will be described below in more details.

The reference signal generator 250 generates a reference signal andoutputs the reference signal to the A/D conversion unit 230. Thereference signal is output through a signal line 23. As this referencesignal, a signal having a voltage decreasing in a ramp shape may beemployed. The reference signal generator 250 starts generation of thereference signal in synchronization with a start of the analog/digitalconversion of the A/D conversion element 231 as described below.

The control unit 260 controls the entire imaging device 1. The controlunit 260 generates a common control signal for controlling the verticalscanning units #1 (210) and #2 (220) and outputs the control signal tothe vertical scanning units #1 (210) and #2 (220) through a signal line24. In addition, the control unit 260 generates a common control signalfor controlling the A/D conversion elements 231 arranged in the A/Dconversion unit 230 and outputs the control signal to all of the A/Dconversion elements 231 through a signal line 25.

The failure detector 280 detects a failure of the signal line 21 on thebasis of an error signal output from the test signal generator 120 orthe like. The failure detector 280 detects a failure in a transfer testsignal line, a reset test signal line, and a pixel selection controlsignal line on the basis of the transfer test signal and the reset testsignal. Detection of a failure may be performed by comparing the testsignal output from the test signal generator 120 or the like with anormal test signal. The configuration of the failure detector 280 willbe described below in more details.

In the imaging device 1 of FIG. 1, the pixel array unit 10 and thedriving unit 20 are formed in different semiconductor chips. The pixelarray unit 10 operates at a relatively high power voltage in order toproduce an image signal. Meanwhile, the driving unit 20 performs adigital signal processing. For this reason, the driving unit 20necessitates a high speed processing and is supplied with a relativelylow power voltage. In this manner, the pixel array unit 10 and thedriving unit 20 are formed from circuits having different properties. Inthis regard, the pixel array unit 10 and the driving unit 20 areseparately formed on each of semiconductor chips manufactured throughappropriate processes. Then, the semiconductor chips are bonded to eachother to form the imaging device 1. As a result, it is possible toimprove cost performance of the imaging device 1. In this case, thesignal lines 11, 21, and 22 perform signal transmission betweendifferent semiconductor chips.

Note that the pixel array unit 10, the vertical scanning units #1 (210)and #2 (220), the A/D conversion unit 230, the test voltage generator240, the reference signal generator 250, the control unit 260, and thefailure detector 280 constitute an image sensor.

The signal processing unit 270 processes the digital image signal outputfrom the A/D conversion element 231. Through this processing, forexample, horizontal transmission can be performed, in which the digitalimage signals output from a plurality of A/D conversion elements 231 aresequentially transmitted. Note that the signal processing unit 270 is anexample of the processing circuit described in the claims.

Configuration of Pixel

FIG. 2 is a diagram illustrating an exemplary configuration of the pixel110 according to the first embodiment of the present technology. In FIG.2, a pixel 110 arranged in the first row of the pixel array unit 10 isillustrated by way of example. The pixel 110 includes a photoelectricconversion element 111, an electric charge storing element 112, anelectric charge transfer element 113, a reset element 114, a signalgeneration element 115, and a signal output element 116. Note that anN-channel metal oxide semiconductor (MOS) transistor may be employed inthe electric charge transfer element 113, the reset element 114, thesignal generation element 115, and the signal output element 116. Theelectric charge transfer element 113, the reset element 114, and thesignal output element 116 can be electrically connected to each other byapplying a voltage equal to or higher than a threshold voltage between asource and a gate of the MOS transistor. This signal having a voltageequal to or higher than the threshold value will be referred to as an“ON” signal.

In addition, the signal lines 21 and 11 are wired to the pixel 110. Thesignal line 21 includes three signal lines including a transfer controlsignal line TR (Transfer), a reset control signal line RST (Reset), anda pixel selection control signal line SEL (select). The transfer controlsignal line TR is a signal line that transmits a transfer control signalas a signal for controlling transfer of electric charges in the electriccharge transfer element 113 as described below. The reset control signalline RST is a signal line that transmits a reset control signal as asignal for controlling a reset operation in the reset element 114. Thepixel selection control signal line SEL is a signal line that transmitsa pixel selection control signal as a signal for controlling an imagesignal output in the signal output element 116. As described above, thesignal lines are arranged for each row. In FIG. 2, these signal linesare identified by the row numbers. For example, “SEL1” denotes the pixelselection control signal line SEL arranged in the first row of the pixelarray unit 10. Furthermore, a power line Vdd and a ground line are wiredto the pixel 110. The power line Vdd is a power line that supplieselectric power necessary in the operations of the signal generationelement 115 and a reset voltage described below.

An anode of the photoelectric conversion element 111 is grounded, and acathode of the photoelectric conversion element 111 is connected to thesource of the electric charge transfer element 113. The gate of theelectric charge transfer element 113 is connected to the transfercontrol signal line TR1, and the drain is connected to the drain of thereset element 114, the gate of the signal generation element 115, andone end of the electric charge storing element 112. The other end of theelectric charge storing element 112 is grounded. The gate of the resetelement 114 is connected to the reset control signal line RST1, and thesource is connected to the power line Vdd. The drain of the signalgeneration element 115 is connected to the power line Vdd, and thesource is connected to the drain of the signal output element 116. Thegate of the signal output element 116 is connected to the pixelselection control signal line SEL1, and the source is connected to thesignal line 11.

The photoelectric conversion element 111 generates and stores electriccharges in response to emitted light. A photodiode may be employed inthe photoelectric conversion element 111.

The electric charge transfer element 113 transfers the electric chargestored in the photoelectric conversion element 111 to the electriccharge storing element 112. The electric charge transfer element 113transfers the electric charge by electrically connecting thephotoelectric conversion element 111 and the electric charge storingelement 112. The electric charge transfer element 113 is controlled bythe transfer control signal transmitted through the transfer controlsignal line TR1. Specifically, in a case where the ON signal is input asthe transfer control signal, the electric charge transfer element 113 iselectrically connected to transfer the electric charge.

The electric charge storing element 112 stores the electric chargetransferred from the electric charge transfer element 113. That is, theelectric charge storing element 112 stores the electric charge generatedby the photoelectric conversion element 111. A floating diffusion regionformed in a diffusion layer of a semiconductor substrate may be employedas the electric charge storing element 112. The electric charge storingelement 112 also serves as a charge-voltage conversion unit. That is,since the electric charge storing element 112 also serves as a straycapacitance, a voltage of the electrode connected to the signalgeneration element 115 out of a pair of electrodes of the electriccharge storing element 112 becomes a voltage that depends on the amountof electric charges stored in the electric charge storing element 112.

The reset element 114 performs a reset operation by discharging electriccharges stored in the electric charge storing element 112. The resetelement 114 discharges electric charges by applying the reset voltage asa voltage supplied from the power line Vdd to the electric chargestoring element 112. Similarly to the electric charge transfer element113, the reset element 114 is controlled by the reset control signaltransmitted through the reset control signal line RST1.

The signal generation element 115 generates a signal that depends on theelectric charges stored in the electric charge storing element 112 as animage signal. The signal generation element 115 generates the imagesignal by amplifying a voltage of the electric charge storing element112 serving as the charge-voltage conversion unit.

The signal output element 116 outputs the image signal generated by thesignal generation element 115 to the signal line 11. Similarly to theelectric charge transfer element 113, the signal output element 116 iscontrolled by the pixel selection control signal transmitted through thepixel selection control signal line SELL

Configuration of Test Signal Generator

FIG. 3 is a diagram illustrating an exemplary configuration of the testsignal generator 120 according to the first embodiment of the presenttechnology. The configuration of the test signal generator 120 issimilar to that of the pixel 110 described in conjunction with FIG. 2except that the photoelectric conversion element 111 is omitted. Inaddition, a signal line 22 is wired to the test signal generator 120, sothat a test voltage is supplied. The electric charge transfer element113 and the drain of the reset element 114 of FIG. 3 are commonlyconnected to the signal line 22.

Generation of the reset test voltage and the transfer test signal in thetest signal generator 120 of FIG. 3 will be described. The reset testsignal is generated in the following sequence. First, the test voltagegenerator 240 supplies the reset test voltage to the test signalgenerator 120. Then, the ON signal is input from the reset controlsignal line RST1, and the reset element 114 is electrically connected,so that the reset test voltage is stored in the electric charge storingelement 112. A signal corresponding to the stored voltage is generatedby the signal generation element 115 as the reset test signal. In thiscase, the reset test signal having a voltage substantially equal to thereset test voltage is generated. The reset test signal is output fromthe signal output element 116 to the signal line 11. The reset voltagemay be employed as the reset test voltage. By commonly using the resettest voltage as the reset voltage, it is possible to simplify theconfiguration of the imaging device 1.

Meanwhile, the transfer test signal is generated in the followingsequence. First, the test voltage generator 240 generates a transfertest voltage and supplies the transfer test voltage to the test signalgenerator 120 through the signal line 22. Then, the ON signal is inputfrom the transfer control signal line TR1, and the electric chargetransfer element 113 is electrically connected, so that the transfertest voltage is stored in the electric charge storing element 112. Asignal corresponding to the voltage stored in the electric chargestoring element 112 is generated by the signal generation element 115 asthe transfer test signal. In this case, since the transfer test voltageis stored in the electric charge storing element 112, a voltagesubstantially equal to the transfer test voltage is generated as thetransfer test signal. A voltage ranging within a dynamic range of theimage signal of the pixel 110 may be employed as the transfer testvoltage. As a result, it is possible to easily perform various types ofprocessing such as analog/digital conversion of the transfer testsignal.

As described above, the test voltage generator 240 changes the testvoltage from the reset test voltage to the transfer test voltage whilethe reset test signal and the transfer test signal are generated. Inthis case, the test voltage generator 240 changes the test voltagebefore a failure detection process on the control signal line in thefailure detector 280. In a case where abnormality occurs in theoperations of the electric charge transfer element 113 and the resetelement 114 due to a failure of the control signal line, the voltage ofthe electric charge storing element 112 changes depending on the testvoltage. In this regard, by reflecting this change on the reset testsignal and detecting it by the failure detector 280, a failure in thetransfer control signal line TR and the reset control signal line RSTcan be detected. In this manner, the test voltage generator 240 changesthe test voltage from the reset test voltage to a test voltage having adifferent voltage when the reset test signal is generated.

In this manner, by adding the test signal generator 120 having aconfiguration similar to that of the pixel 110, it is possible to detecta failure in the signal line 21 and reduce a change of the layout or thelike of the pixel array unit 10. Note that, since the configuration ofthe test signal generator 130 is similar to that of the test signalgenerator 120, it will not be described repeatedly.

Note that the electric charge transfer element 113 is an example of atransfer test signal generator described in the claims. The resetelement 114 is an example of a reset test signal generator described inthe claims. In addition, the electric charge storing element 112 is anexample of a capacitor described in the claims.

Configuration of Vertical Scanning Unit

FIG. 4 is a diagram illustrating an exemplary configuration of thevertical scanning unit 210 according to an embodiment of the presenttechnology. The vertical scanning unit 210 includes an address decoder211 and a pixel driving unit 212.

The address decoder 211 generates a signal for selecting a row of thepixel array unit 10 and outputs it to the pixel driving unit 212. Theaddress decoder 211 is connected to the pixel driving unit 212 through aplurality of signal lines corresponding to the rows of the pixel arrayunit 10 to sequentially select the signal lines and output the signal,so that the row of the pixel array unit 10 is selected. For example, ashift register may be employed in the address decoder 211.

The pixel driving unit 212 generates a control signal for the pixel 110and outputs the control signal through the signal line 21. The pixeldriving unit 212 generates the transfer control signal, the resetcontrol signal, and the pixel selection control signal described aboveas the control signals and outputs the control signals to the transfercontrol signal line TR, the reset control signal line RST, and the pixelselection control signal line SEL, respectively, as illustrated in FIG.4. The pixel driving unit 212 outputs the control signal generated tothe signal line 21 wired to the pixel 110 corresponding to the rowselected by the address decoder 211 out of the signal lines.

Note that the configuration of the vertical scanning unit 220 is similarto that of the vertical scanning unit 210, and it will not be describedrepeatedly.

Configuration of A/D Conversion Unit

FIG. 5 is a diagram illustrating an exemplary configuration of the A/Dconversion unit 230 according to the first embodiment of the presenttechnology. This A/D conversion unit 230 includes constant current powersources 232 and A/D conversion elements 231. The constant current powersources 232 and the A/D conversion elements 231 are arranged for eachsignal line 11.

The constant current power sources 232 are connected between the signalline 11 and the ground to serve as a load of the signal output element116 in the pixels 110 and the test signal generators 120 and 130.

The A/D conversion elements 231 perform analog/digital conversion forthe image signal and the test signal. The A/D conversion elements 231are controlled by the control unit 260 such that the reference signalgenerated from the reference signal generator 250 is compared with animage signal or the like, and a digital signal generated on the basis ofthe comparison result is output as a result of the analog/digitalconversion. Out of the A/D conversion elements 231 of FIG. 5, the A/Dconversion element 231 connected to the pixel 110 generates a digitalimage signal. In FIG. 5, the A/D conversion elements 231 other thanthose arranged in both ends generate the digital image signals andoutput the digital image signals to the signal processing unit 270through the signal line 26. Meanwhile, the A/D conversion element 231connected to the test signal generator 120 or the like generates adigital test signal. In FIG. 5, the A/D conversion elements 231 arrangedin both ends generate digital test signals and output the digital testsignals to the failure detector 280 through the signal lines 27 and 28.

Configuration of A/D Conversion Element

FIG. 6 is a diagram illustrating an exemplary configuration of the A/Dconversion element 231 according to an embodiment of the presenttechnology. The A/D conversion element 231 includes capacitors 301 and302, a comparison element 303, and a count element 304.

The capacitors 301 and 302 are coupling capacitors. The capacitor 301 isconnected between the signal line 11 and an input of the comparisonelement 303 to transmit the image signal or the test signal to thecomparison element 303. In addition, the capacitor 302 is connectedbetween the signal line 23 and an input of the comparison element 303 totransmit the reference signal to the comparison element 303.

The comparison element 303 compares the image signal or the test signalwith the reference signal. The comparison element 303 outputs a resultof the comparison to the count element 304. Specifically, in a casewhere a voltage of the image signal or the like is lower than a voltageof the reference signal, a value “0” may be output. In a case where thevoltage of the image signal or the like is higher than the voltage ofthe reference signal, a value “1” may be output as the result of thecomparison.

The count element 304 counts time from the start of the analog/digitalconversion of the A/D conversion element 231 to the output of thecomparison result from the comparison element 303. This time counting isperformed by counting a clock signal (not shown). Along with the startof the analog/digital conversion of the A/D conversion element 231, thereference signal having a voltage decreasing in a ramp shape starts tobe output from the reference signal generator 250 and is compared withthe image signal or the like by the comparison element 303. Then, whenthe output value of the comparison element 303 changes from “0” to “1,”the count element 304 stops the counting. The voltage of the imagesignal or the like in this case is substantially equal to the voltage ofthe reference signal. Since the voltage of the reference signal matchesthe count value of the count element 304 one to one, this count valuebecomes a digital value corresponding to the voltage of the image signalor the like. This digital value is output as a result of theanalog/digital conversion of the image signal or the like. In thismanner, the A/D conversion element 231 performs the analog/digitalconversion. The count element 304 is controlled by the control signalfrom the control unit 260 to perform the analog/digital conversiondescribed above.

When the A/D conversion element 231 performs analog/digital conversionfor the image signal, correlated double sampling (CDS) is performed toremove noise unique in the pixel 110. This CDS may be performed in thefollowing manner. First, analog/digital conversion is performed for areset operation image signal which is a signal output to the signal line11 during a reset operation of the pixel 110, and a result of thecomparison is stored in the count element 304. Then, the count valuestored in the count element 304 is inverted on a bit-by-bit basis. Then,analog/digital conversion is performed for the image signal generatedwhen an electric charge generated by the photoelectric conversionelement 111 is transmitted to the electric charge storing element 112.In this case, the count element 304 starts the counting by using theinverted count value as an initial value and subtracts the resetoperation image signal from the image signal. As a result, the CDS isexecuted. The digital image signal subjected to the CDS is output to thesignal processing unit 270.

In addition, when the A/D conversion element 231 performs analog/digitalconversion for the test signal, analog/digital conversion for the resettest signal output to the signal line 11 after the reset operation, andanalog/digital conversion for the transfer test signal output to thesignal line 11 after transmission of the electric charge aresequentially performed, so that a digital reset test signal and adigital transfer test signal are output to the failure detector 280.

In this manner, the A/D conversion element 231 performs analog/digitalconversion for the signal output from the connected pixel 110 and thetest signal generator 120 or the like and outputs the converted digitalsignal.

Configuration of Failure Detector

FIG. 7 is a diagram illustrating an exemplary configuration of thefailure detector 280 according to the first embodiment of the presenttechnology. The failure detector 280 includes a test voltage storingelement 281, comparison elements #1 (282) and #2 (283), and a failureinformation generator 284.

The test voltage storing element 281 stores the test voltage generatedby the test voltage generator 240. The test voltage storing element 281stores digital values corresponding to a transmission control testvoltage and a reset control test voltage and outputs them to thecomparison elements #1(282) and #2 (283).

The comparison elements #1 (282) and #2 (283) compare the test signaland the test voltage. The comparison element #1 (282) is connected tothe signal line 27. The test signal generated by the test signalgenerator 120 is subjected to analog/digital conversion, and the digitaltest signal is input to the comparison element #1 (282). Meanwhile, thecomparison element #2 (283) is connected to the signal line 28. The testsignal generated by the test signal generator 130 is subjected toanalog/digital conversion, and the digital test signal is input to thecomparison element #2 (283).

As described in conjunction with FIG. 3, the transfer test signal andthe reset test signal having voltages substantially equal to thetransfer test voltage and the reset test voltage, respectively, areoutput from the test signal generator 120 or the like during a normaloperation. However, in a case where a failure such as disconnectionoccurs in the transfer control signal line TR and the reset controlsignal line RST, the transfer test signal and the reset test signalhaving values different from the transfer test voltage and the resettest voltage, respectively, are output from the test signal generator120 or the like. The comparison element #1 (282) or the like in FIG. 7compares the transfer test signal and the reset test signal with thetransfer test voltage and the reset test voltage, respectively, andoutputs a comparison result to the failure information generator 284.

The failure information generator 284 generates and outputs failureinformation as information on a failure in the transfer control signalline TR or the like on the basis of the comparison result output fromthe comparison elements #1 (282) and #2 (283). The failure informationgenerator 284 detects a failure in the transfer control signal line TR,for example, in a case where the transfer test signal is different fromthe transfer test voltage. In this case, the failure informationgenerator 284 may output information indicating that a failure occurs inthe transfer control signal line TR as the failure information. Inaddition, information on the row where the failure occurs may begenerated by providing a row counter or the like that stores a targetoutput row of the control signal in the vertical scanning unit #1 (210)or the like.

Configurations of Pixel Array Unit and Driving Units

FIG. 8 is a diagram illustrating exemplary configurations of the pixelarray unit 10 and the driving unit 20 according to an embodiment of thepresent technology. FIG. 8 shows wiring states of the signal lines 21and 11 in the pixel array unit 10 and the driving unit 20. The wiringstate of the signal line 21 will be described by exemplifying the pixelselection control signal line SEL.

The pixel selection control signal line SEL includes wire lines 170,291, and 292 and connection terminals 160. The wire line 170 is formedin the pixel array unit 10 and is wired commonly between the gates ofthe signal output elements 116 of the pixels 110 and the test signalgenerator 120 or the like. The wire lines 291 and 292 are formed in thedriving unit 20 and are connected to the vertical scanning units #1(210) and #2 (220), respectively. The connection terminals 160 are usedto connect the wire line 170 and the wire lines 291 and 292 to eachother. The connection terminals 160 are used to transmit signals betweendifferent semiconductor chips. Similarly to the signal line 21, signaltransmission on the signal line 11 is also performed through theconnection terminals 160. As the connection terminal 160, for example, avia hole penetrating through the semiconductor chip or a pad formed on asurface of the semiconductor chip and connected by performing a thermalpress bonding process may be employed. The transfer control signal lineTR and the reset control signal line RST may have configurations similarto that of the pixel selection control signal line SEL described above.

In FIG. 8, even in a case where a failure such as disconnection occursbetween the test signal generators 120 and 130, that is, in an areawhere a plurality of pixels 110 are arranged on the wire line 170, thecontrol signals output from each of the vertical scanning units #1 (210)and #2 (220) are transmitted. For this reason, the transmission of thecontrol signal is not interrupted, and the image signal is generatednormally. As illustrated in FIG. 8, the signal line 21 is connectedcommonly to the vertical scanning unit #1 (210), the test signalgenerator 120, the pixel 110, the test signal generator 130, and thevertical scanning unit #2 (220) in this order. As a result, in a casewhere the wire line 170 is disconnected between the test signalgenerators 120 and 130, a failure in the test signal generator 120 orthe like is not detected, and it is possible to avoid unnecessaryfailure information from being output.

In contrast, in a case where a failure such as poor connection occurs ina pair of connection terminals 160 arranged in the signal line 21, thecontrol signals output from the vertical scanning units #1 (210) and #2(220) are not transmitted to the wire line 170. In this case, it ispossible to detect a failure in the test signal generator 120 or thelike. In addition, in a case where one of the connection terminals 160is failed, the control signal is transmitted through the otherconnection terminal 160. Therefore, it is possible to generate an imagesignal from the pixel 110, and a failure in the test signal generator120 or the like is not detected. However, in order to improvereliability of the imaging device 1, it is necessary to detect a failurestate in a single connection terminal 160. In this case, a failure maybe detected by using a transfer time of the control signal. Since ittakes time to transfer the control signal output from the verticalscanning unit #1 (210) or the like, a settling time of the test signaloutput from the test signal generator 120 or the like arranged in thevicinity of a failed connection terminal 160 is longer than the settlingtime of the test signal output from the test signal generator 120 or thelike arranged in the vicinity of an unfailed connection terminal 160. Itis possible to detect a failure state of a single connection terminal160 by detecting a failure using the failure detector 280 within a timeperiod shorter than this settling time.

Configuration of Connection Terminal

FIG. 9 is a diagram illustrating an exemplary configuration of theconnection terminal 160 according to an embodiment of the presenttechnology. FIG. 9 is a schematic diagram illustrating a cross-sectionalconfiguration of the imaging device 1 and shows a configuration of thesignal line 21 in a coupling element between the pixel array unit 10 andthe driving unit 20.

“a” of FIG. 9 illustrates an example in which the connection terminal160 includes a pair of via holes. The pixel array unit 10 includesinsulation layers 191 and 195 and a well region 192. The well region 192is formed of a P-type semiconductor, and N-type semiconductor regions193 and 194 are formed in the drain and source regions, respectively, ofthe signal output element 116. The insulation layer 195 includes anelectrode 196 serving as the gate of the signal output element 116,via-hole plugs 171 and 173, and a wire line 172. The via-hole plugs 171and 173 and the wire line 172 are included in the wire line 170.

The connection terminal 160 includes pads 161 and 163 formed in theinsulation layers 195 and 191, respectively, of the pixel array unit 10,via holes 162 and 164, and a pad 165 formed in the driving unit 20. Thepad 161 is connected to the via-hole plug 173. The pads 161 and 163 areconnected to each other through the via hole 162, and the pads 163 and165 are connected to each other through the via hole 164.

The driving unit 20 of FIG. 9 is illustrated by simplifying aconfiguration of the vicinity of the signal line 21. The wire line 291of FIG. 9 connects the pad 165 and the vertical scanning unit 210 toeach other. In this manner, the pads 161, 163, and 165 are connected toeach other through the via holes 162 and 164 to transmit the controlsignal.

“b” of FIG. 9 illustrates an example in which the connection terminal160 includes a single via hole. In “b” of FIG. 9, the via hole 164connects the pads 161 and 165 to each other. Compared to theconfiguration of “a” of FIG. 9, it is possible to shorten amanufacturing process and reduce an area occupied by the connectionterminal 160.

FIG. 10 is a diagram illustrating another exemplary configuration of theconnection terminal 160 according to an embodiment of the presenttechnology. The connection terminal 160 of FIG. 10 includes pads 166 and167. The pad 166 is formed on a chip surface of the pixel array unit 10,and the pad 167 is formed on a chip surface of the driving unit 20. Whenthe pixel array unit 10 and the driving unit 20 are bonded to each otherthrough a thermal press bonding process, the pads 166 and 167 areelectrically bonded to each other to allow signal transmission. Unlikethe via hole of FIG. 9, it is not necessary to form a through-hole inthe semiconductor chip. Therefore, it is possible to arrange theconnection terminal 160 in an arbitrary position of the chip.

In this manner, using the connection terminal 160 including the viaholes 162 and 164 and the pads 166 and 167 bonded through a thermalpress bonding process, it is possible to perform signal transmissionbetween different chips. However, since such connection terminals 160are formed between different chips, a stress is concentrated, and afailure such as poor connection may easily occur. In this regard, afailure is detected by arranging the test signal generator 120 or thelike in the pixel array unit 10. Note that detection of a failure usingthe test signal generator 120 or the like is also effective in detectionof an initial defect of the imaging device 1.

Generation of Image Signal and Test Signal

FIG. 11 is a diagram illustrating an example of generation of the imagesignal and the test signal according to an embodiment of the presenttechnology. In FIG. 11, “SEL1,” “RST1,” and “TR1” denote control signalsfor the pixel selection control signal line SEL, the reset controlsignal line RST, and the transfer control signal line TR, respectively,arranged in the first row of the pixel array unit 10. The elementsindicated by the value “1” in these binary waveforms correspond to theinput of the ON signal. In addition, “SEL2,” “RST2,” and “TR2” denotecontrol signals of the signal lines arranged in the second row of thepixel array unit 10. In addition, “Vtest” refers to a test voltagesupplied from the test voltage generator 240. In the waveform of thistest voltage, a high voltage element corresponds to a period ofsupplying the reset test voltage, and a low voltage element correspondsto a period of supplying the transfer test voltage. The waveforms of the“ELECTRIC CHARGE STORING ELEMENT (PIXEL)” and the “IMAGE SIGNAL”indicate a voltage of the electric charge storing element 112 and theimage signal of the pixel 110 arranged in the first row, respectively.The waveforms of the “ELECTRIC CHARGE STORING ELEMENT (TEST SIGNALGENERATOR)” and the “TEST SIGNAL” indicate a voltage of the electriccharge storing element 112 and a test signal of the test signalgenerator 120 arranged in the first row, respectively. In addition, inFIG. 11, it is assumed that a reset test voltage having a value equal tothe voltage supplied from the power line Vdd (hereinafter, referred toas “Vdd”) to the pixel 110 is supplied to the test signal generator 120.

At the timing T0, all of the control signal lines are set to “0,” andthe test voltage generator 240 supplies the voltage Vdd as the resettest voltage. This state corresponds to an initial state.

At the timing T1 to T5, the ON signal is input from the reset controlsignal line RST1 and the transfer control signal line TR1, so that theelectric charge storing element 112 and the photoelectric conversionelement 111 of the pixel 110 are reset. As a result, exposure of thepixels 110 arranged in the first row starts. This reset operationincreases the voltage of the electric charge storing element 112 of thepixel 110 to Vdd. The electric charge storing element 112 of the testsignal generator 120 is also reset, and its voltage increases to Vdd(T1). Then, the input of the ON signal from the reset control signalline RST1 and the transfer control signal line TR1 stops (T2 to T5). Thevoltages of the electric charge storing elements 112 of the pixel 110and the test signal generator 120 are maintained at Vdd. Note that theoperations of the pixels 110 and the like arranged in the second row ofthe pixel array unit 10 will be described below.

At the timing T5 to T7, the ON signal is input from the reset controlsignal line RST1, and the electric charge storing elements 112 of thepixel 110 and the test signal generator 120 are reset again (T5). Inaddition, the ON signal is input from the pixel selection control signalline SEL1, and an image signal corresponding to the voltage of theelectric charge storing element 112 of the pixel 110 is output.Similarly, a test signal corresponding to the voltage of the electriccharge storing element 112 of the test signal generator 120 is output.This test signal corresponds to the reset test signal. The ON signal iscontinuously input from this pixel selection control signal line SEL1until the timing T11. Then, the input of the ON signal from the resetcontrol signal line RST1 stops (T6). As a result, the reset operationimage signal corresponding to the voltage of the electric charge storingelement 112 of the pixel 110 is output. At the same time, a reset testvoltage corresponding to the voltage of the electric charge storingelement 112 of the test signal generator 120 is generated and output.Meanwhile, the test voltage generator 240 changes the supplied testvoltage from the reset test voltage to the transfer test voltage (T6 toT7).

At the timing T7 to T8, the reset operation image signal output from thepixel 110 is subjected to analog/digital conversion, and the conversionresult is stored in the count element 304. At the same time, the resettest voltage output from the test signal generator 120 is subjected toanalog/digital conversion and is output to the failure detector 280.

At the timing T8 to T9, the ON signal is input from the transfer controlsignal line TR1, and the electric charge generated from thephotoelectric conversion element 111 is transferred to the electriccharge storing element 112. An image signal corresponding to thetransferred electric charges is output. Meanwhile, in the test signalgenerator 120, the transfer test voltage is applied to the electriccharge storing element 112 to generate and output the transfer testsignal.

At the timing T9 to T10, the image signal output from the pixel 110 issubjected to analog/digital conversion to output the digital imagesignal to the signal processing unit 270. Meanwhile, the transfer testsignal output from the test signal generator 120 is subjected toanalog/digital conversion and is output to the failure detector 280.

At the timing T10 to T11, the test voltage generator 240 changes thetest voltage from the transfer test voltage to the reset test voltage.Then, the input operation of the ON signal to the pixel selectioncontrol signal line SEL1 stops (T11).

Note that, similarly to the timing T1 to T11, at the timing T3 to T18,the control signal is input to the pixel selection control signal lineSEL2, the reset control signal line RST2, and the transfer controlsignal line TR2 to generate the image signal and the test signal for thesecond row. A driving method in which exposure and generation of theimage signal are performed sequentially for each row in this manner iscalled a rolling shutter method. An image signal corresponding to asingle screen can be generated by driving all of the rows of the pixelarray unit 10 using the rolling shutter method. Note that the testsignal generator 130 also generates the test signal in a similar mannerto the test signal generator 120.

In this manner, when the control signal is transmitted through the pixelselection control signal line SEL, the reset control signal line RST,and the transfer control signal line TR, the reset test signal and thetransfer test signal are generated as illustrated in FIG. 11. However,in a case where the control signal is not appropriately transmitted dueto a failure in the signal line, a test signal different from thatillustrated in FIG. 11 is generated.

Test Signal when Transfer Control Signal Line is Failed

FIG. 12 is a diagram illustrating an example of the test signal when thetransfer control signal line is failed according to an embodiment of thepresent technology. “a” of FIG. 12 illustrates a case where the value ofthe transfer control signal is fixed to “1” due to a failure in thetransfer control signal line TR1, that is, a waveform exhibited when thetransfer control signal line TR1 suffers from a stuck-at fault to “1.”This corresponds to a case where a short-circuit is generated betweenthe transfer control signal line TR1 and the power line Vdd. Inaddition, “b” of FIG. 12 illustrates a case where the value of thetransfer control signal is fixed to “0” due to a failure in the transfercontrol signal line TR1, that is, a waveform exhibited when the transfercontrol signal line TR1 suffers from a stuck-at fault to “0.” Thiscorresponds to a case where the transfer control signal line TR1 isdisconnected. In FIG. 12, the waveforms indicated by the dotted lineindicate a case where a failure does not occur. These waveformscorrespond to those described in conjunction with FIG. 11.

In “a” of FIG. 12, the ON signal is input from the transfer controlsignal line TR1 at all times. For this reason, at the timing T6 to T8,the reset test signal has a voltage substantially equal to the transfertest voltage supplied from the test voltage generator 240. That is, thereset test signal has a voltage different the reset test voltage. Inthis case, the reset test signal and the reset test voltage are comparedusing the comparison elements #1 (282) and #2 (283) described inconjunction with FIG. 7 to detect a failure in the transfer controlsignal line TR1.

In “b” of FIG. 12, since the ON signal is not input from the transfercontrol signal line TR1, the transfer test signal has a voltagesubstantially equal to the reset test voltage at the timing T8 to T10.That is, the transfer test signal has a voltage different from thetransfer test voltage. In this case, the transfer test signal and thetransfer test voltage are compared using the comparison elements #1(282) and #2 (283) to detect a failure in the transfer control signalline TR1.

Test Signal when Reset Control Signal Line is Failed

FIG. 13 is a diagram illustrating an example of the test signal when thereset control signal line is failed according to an embodiment of thepresent technology. “a” of FIG. 13 illustrates a waveform exhibited whenthe reset control signal line RST suffers from a stuck-at fault to “1.”“b” of FIG. 13 illustrates a waveform exhibited when the reset controlsignal line RST suffers from a stuck-at fault to “0.”

In “a” of FIG. 13, since the ON signal is input from the reset controlsignal line RST1 at all times, the reset test signal has a voltagesubstantially equal to the transfer test voltage at the timing T6 to T8.That is, the reset test signal has a voltage different from the resettest voltage. In this case, the reset test signal and the reset testvoltage are compared using the comparison elements #1 (282) and #2(283).

In “b” of FIG. 13, since the ON signal is not input from the resetcontrol signal line RST1, the reset test signal has a voltagesubstantially equal to the transfer test voltage stored in the electriccharge storing element 112 when the previous control signal is input atthe timing T6 to T8. That is, the reset test signal has a voltagedifferent from the reset test voltage. In this case, the reset testsignal and the reset test voltage are compared using the comparisonelements #1 (282) and #2 (283). Note that, in “b” of FIG. 13, it isassumed that exposure for the first row starts when the test voltagegenerator 240 supplies the transfer test voltage at the timing T1 to T2.

Test Signal when Pixel Selection Control Signal Line is Failed

FIG. 14 is a diagram illustrating an example of the test signal when thepixel selection control signal line is failed according to an embodimentof the present technology. FIG. 14 illustrates a waveform exhibited whenthe pixel selection control signal line SEL1 is not failed, and thepixel selection control signal line SEL2 suffers from a stuck-at faultto “1.” In addition, the waveforms of the “ELECTRIC CHARGE STORINGELEMENT #1” and the “ELECTRIC CHARGE STORING ELEMENTS #2” indicatevoltages of the electric charge storing elements 112 of the test signalgenerators 120 arranged in the first and second rows, respectively.Since the ON signal is input from the pixel selection control signalline SEL2 at all times, a signal corresponding to the voltage of theelectric charge storing element 112 of the test signal generator 120arranged in the second row is output to the signal line 11 at the timingT3 to T15. As a result, at the timing T8 to T11, the signal outputelement 116 of the test signal generator 120 arranged in the first rowhas an OFF state, and the transfer test signal has a voltagesubstantially equal to the reset test voltage. That is, the transfertest signal has a voltage different from the transfer test voltage. Inthis case, the transfer test signal and the transfer test voltage arecompared using the comparison elements #1 (282) and #2 (283).

Meanwhile, at the timing T12 to T18, the reset test signal and thetransfer test signal are normally output from the test signal generator120 arranged in the second row.

In this manner, a stuck-at fault to “1” in the pixel selection controlsignal line SEL can be detected by outputting the normal transfer testsignal in the failed row and outputting the transfer test signal havinga voltage substantially equal to the reset test voltage in other rows.

FIG. 15 is a diagram illustrating another example of the test signalwhen the pixel selection control signal line is failed according to anembodiment of the present technology. FIG. 15 illustrates a waveformexhibited when a stuck-at fault to “0” occurs in the pixel selectioncontrol signal line SELL Since the ON signal is not input from the pixelselection control signal line SEL1, the reset test signal and thetransfer test signal having a substantially equal voltage are output.That is, the reset test signal has a voltage different from the resettest voltage. In this case, the reset test signal and the reset testvoltage are compared using the comparison elements #1 (282) and #2(283).

As described above in conjunction with FIGS. 12 to 15, the reset testsignal and the transfer test signal are compared with the reset testvoltage and the transfer test voltage, respectively, using thecomparison elements #1 (282) and #2 (283). Therefore, it is possible todetect a failure in the transfer control signal line TR, the resetcontrol signal line RST, and the pixel selection control signal lineSEL.

In this manner, according to the first embodiment of the presenttechnology, the transfer test signal and the reset test signal aregenerated from the transfer control signal and the reset control signal,respectively, using the test signal generator applied with the testvoltage. It is possible to detect a failure in the transfer controlsignal line and the reset control signal line by comparing the transfertest signal and the reset test signal with the normal transfer testsignal and the normal reset test signal.

2. Second Embodiment

In the first embodiment described above, the control signal is suppliedto the pixel array unit 10 from a pair of vertical scanning units #1(210) and #2 (220). In contrast, the control signal may be supplied froma single vertical scanning unit. The second embodiment of the presenttechnology is different from the first embodiment described above inthat the number of vertical scanning units is reduced by one.

Configuration of Imaging Device

FIG. 16 is a diagram illustrating an exemplary configuration of theimaging device 1 according to the second embodiment of the presenttechnology. In FIG. 16, the imaging device 1 is different from theimaging device 1 described in conjunction with FIG. 1 as describedbelow. The imaging device 1 of FIG. 16 does not necessarily have thevertical scanning unit #2 (220). In addition, in the imaging device 1 ofFIG. 16, the pixel array unit 10, the vertical scanning unit 210, theA/D conversion unit 230, the test voltage generator 240, the referencesignal generator 250, the control unit 260, the signal processing unit270, and the failure detector 280 are formed in the same semiconductorchip.

The test signal generator 120 is arranged for each row of the pixelarray unit 10 of FIG. 16. In addition, the signal line 21 is commonlyconnected to the vertical scanning unit 210, the pixel 110, and the testsignal generator 120 in this order. That is, the test signal generator120 is connected to a terminated end portion of the signal line 21. As aresult, it is possible to improve failure detection accuracy of thesignal line 21.

The A/D conversion unit 230 of FIG. 16 performs analog/digitalconversion for the test signal transmitted through a single signal line11 and outputs the digital test signal to the failure detector 280through the signal line 27. The failure detector 280 of FIG. 16 detectsa failure on the basis of the digital test signal transmitted throughthe signal line 27. Since the imaging device 1 of FIG. 16 includes asingle semiconductor chip, it is not necessary to provide a connectionterminal 160 of the signal line 21. For this reason, compared to theimaging device 1 of FIG. 1, a failure rate of the signal line 21 isreduced. In this regard, it is possible to omit one of a pair ofvertical scanning units. As a result, it is possible to simplify theconfiguration of the imaging device 1.

Other configurations of the imaging device 1 are similar to those of theimaging device 1 of the first embodiment of the present technology, andthey will not be described repeatedly.

In this manner, according to the first embodiment of the presenttechnology, it is possible to simplify the configuration of the imagingdevice 1 by reducing one of the vertical scanning units by forming theimaging devices 1 in the same semiconductor chip.

3. Third Embodiment

In the first embodiment described above, the image signals are generatedsequentially from the rows of the pixel array unit 10, and theanalog/digital conversion for the image signal is performed for eachrow. In contrast, the pixels 110 of the pixel array unit 10 may bedivided into a plurality of areas, and generation of the image signaland the analog/digital conversion may be performed for each dividedarea. The third embodiment of the present technology is different fromthe first embodiment described above in that generation of the imagesignal or the like is performed for each area.

Configuration of Imaging Device

FIG. 17 is a diagram illustrating an exemplary configuration of theimaging device 1 according to the third embodiment of the presenttechnology. The imaging device 1 of FIG. 17 is different from theimaging device 1 of FIG. 1 in that the imaging device 1 has a pluralityof A/D conversion units 230.

In the pixel array unit 10 of FIG. 17, pixel units 410 instead of thepixels 110 are arranged in a matrix shape. In addition, a failuredetection unit 420 is arranged for each row instead of the test signalgenerators 120 and 130. In addition, the signal lines 21 and 22 arewired to the pixel units 410 and the failure detection units 420 in asimilar manner to the pixel array units 10 described in conjunction withFIG. 1.

In the imaging device 1 of FIG. 17, the A/D conversion units 230 arearranged to mate with the pixel units 410 and the failure detectionunits 420 of the pixel array unit 10 to perform analog/digitalconversion for each image signal or the like and output each of theconverted image signals or the like to the signal processing unit 270 orthe failure detector 280. The pixel units 410, the failure detectionunits 420, and the A/D conversion units 230 mating with the pixel units410 and the failure detection units 420 are wired individually throughthe signal line 11.

Configuration of Pixel Unit

FIG. 18 is a diagram illustrating an exemplary configuration of thepixel unit 410 according to the third embodiment of the presenttechnology. The pixel unit 410 includes pixels 110 arranged in a matrixshape. In FIG. 18, it is assumed that 10?10 pixels 110 are arranged. Thepixel selection control signal line SEL and the reset control signalline RST are arranged for each row and are wired commonly to the pixels110 arranged in a single row. In FIG. 18, the pixel selection controlsignal line SEL and the reset control signal line RST are identified byassigning the row number of the pixel unit 410 and the row number of thepixel 110. For example, the pixel selection control signal line SEL1_2denotes the pixel selection control signal line SEL wired to the pixel110 of the second row in the pixel unit 410 of the first row.

Meanwhile, the transfer control signal line TR is arranged for eachpixel 110. In FIG. 18, the transfer control signal line TR is identifiedby assigning the row number of the pixel unit 410 and the row number ofthe pixel 110. For example, the transfer control signal line TR1_2denotes the transfer control signal line TR wired to the pixel 110arranged in the first row and the second column in the pixel unit 410 ofthe first row. Note that the pixel selection control signal line SEL,the reset control signal line RST, and the transfer control signal lineTR are wired commonly to the pixel units 410 arranged in the same row.

In addition, in the pixel unit 410, the signal lines 11 are arranged foreach column and are wired commonly to the pixels 110 arranged in thecolumn.

Configuration of Failure Detection Unit

FIG. 19 is a diagram illustrating an exemplary configuration of thefailure detection unit 420 according to the third embodiment of thepresent technology. The failure detection unit 420 is formed byarranging the test signal generators 120 in a matrix shape. In addition,The pixel selection control signal line SEL, the reset control signalline RST, and the transfer control signal line TR described inconjunction with FIG. 18 are arranged in the failure detection unit 420in the similar manner, and wired to each test signal generator 120. Inaddition, the signal line 22 is wired commonly to each test signalgenerator 120 to supply the test voltage.

Configuration of A/D Conversion Unit

FIG. 20 is a diagram illustrating an exemplary configuration of the A/Dconversion unit 230 according to the third embodiment of the presenttechnology. The A/D conversion unit 230 of FIG. 20 is different from theA/D conversion unit 230 described in conjunction with FIG. 5 in that theA/D conversion unit 230 is provided with a selector 233 and a single A/Dconversion element 231.

The selector 233 is used to select the signal line 11 wired between thepixel units 410 or the failure detection units 420. The selector 233outputs the image signal or the like transmitted through the selectedsignal line 11 to the A/D conversion element 231. In addition, theselector 233 sequentially selects the signal lines 11 arranged in eachcolumn of the pixel units 410 or the like. As the row of the pixel 110or the like is selected using the pixel selection control signal lineSEL, and the column of the pixel 110 or the like is selected using theselector 233 as described in conjunction with FIG. 18, a single pixel110 of the pixel unit 410 or the like is selected, so that an imagesignal is transmitted to the A/D conversion element 231.

Generation of the image signal in the pixel unit 410 is performedthrough a rolling shutter type processing in the arranged pixels 110.Specifically, a series of processing at the timing T1 to T11 in FIG. 11is sequentially performed for the pixel 110 arranged in the first rowand the first column to the pixel 110 arranged in the tenth row and thetenth column in FIG. 18. In addition, a series of processing for thepixel 110 arranged in the first row and the first column to the pixel110 arranged in the tenth row and the tenth column is simultaneouslyperformed for all of the pixel units 410 arranged in the pixel arrayunit 10.

In the imaging device 1 according to the first embodiment of the presenttechnology, the rolling shutter type processing on a row-by-row basis isexecuted for all of the pixels 110 arranged in the pixel array unit 10.In this case, since an exposure time is different between the first rowand the last row, an image obtained by photographing a moving object hasa distortion. A similar distortion is also generated in the imagingdevice 1 of the third embodiment of the present technology. However,since the rolling shutter type processing on a pixel-by-pixel basis isexecuted for each pixel unit 410, the difference of the exposure time isrelatively reduced. For this reason, it is possible to reduce an imagedistortion.

In addition, in the imaging device 1 according to the third embodimentof the present technology, the transfer control signal line TR or thelike is wired to the vertical scanning unit #1 (210), the test signalgenerator 120, the pixel 110, the test signal generator 120, and thevertical scanning unit #2 (220) in this order to detect a failure.

Other configurations of the imaging device 1 are similar to those of theimaging device 1 of the first embodiment of the present technology, andthey will not be described repeatedly.

In this manner, according to the third embodiment of the presenttechnology, it is possible to improve image quality of the image signalby generating the image signal for each area of the pixel array unit 10.

4. Fourth Embodiment

In the first embodiment described above, the analog/digital conversionis performed for the test signal output from the test signal generator120 or the like. In contrast, a failure may be detected by directlyusing the test signal output from the test signal generator 120 or thelike. The fourth embodiment of the present technology is different fromthe first embodiment described above in that the analog/digitalconversion of the test signal is omitted.

Configuration of Imaging Device

FIG. 21 is a diagram illustrating an exemplary configuration of theimaging device 1 according to the fourth embodiment of the presenttechnology. The imaging device 1 of FIG. 21 is different from theimaging device 1 described in conjunction with FIG. 1 in that it is notnecessary to provide the A/D conversion elements 231 corresponding tothe test signals output from the test signal generators 120 and 130, andeach test signal generated from each test signal generator 120 istransmitted to the failure detector 280.

Configuration of Failure Detector

FIG. 22 is a diagram illustrating an exemplary configuration of thefailure detector 280 according to the fourth embodiment of the presenttechnology. The failure detector 280 of FIG. 22 is different from thefailure detector 280 described in conjunction with FIG. 7 in that asignal shaping element 285 and an encoder 286 are provided instead ofthe test voltage storing element 281 and the comparison elements #1(282) and #2 (283). In addition, the failure detector 280 of FIG. 22 hasa failure information generator 287 instead of the failure informationgenerator 284.

The signal shaping element 285 shapes each test signal output from thetest signal generators 120 and 130. The signal shaping element 285shapes the test signal into a digital test signal having an H-level oran L-level by comparing the test signal with a predetermined thresholdvalue. A comparator arranged in each signal line 12 may be used in thesignal shaping element 285.

The encoder 286 encodes the digital test signal shaped by the signalshaping element 285. The encoder 286 encodes the test signal for eachsignal line 12 that transmits the test signal through the signal shapingelement 285. Specifically, when a test signal is input, a row number ofthe test signal generator 120 or the like connected to the signal line12 that transmits the test signal is generated and output. For example,when a transfer test signal having an L-level is input at the timing T7to T8 in “a” of FIG. 12, the encoder 286 detects this L-level signal andoutputs the row number corresponding to the signal line 12 thattransmits the transfer test signal.

The failure information generator 287 generates failure information fromthe row number output from the encoder 286 and outputs the failureinformation.

Other configurations of the imaging device 1 are similar to those of theimaging device 1 of the first embodiment of the present technology, andthey will not be described repeatedly.

In this manner, according to the fourth embodiment of the presenttechnology, it is possible to omit the analog/digital conversion for thetest signal by detecting a failure by encoding the test signal outputfrom the test signal generator 120 or the like. As a result, it ispossible to simplify the configuration of the imaging device 1.

5. Fifth Embodiment

In the first embodiment described above, a failure in the control signalline is detected, and the failure information is output. In contrast,correction may be performed for the image signal of the failed row. Thefourth embodiment of the present technology is different from the firstembodiment described above in that correction is performed for the imagesignal on the basis of the failure information.

Configuration of Imaging Device

FIG. 23 is a diagram illustrating an exemplary configuration of theimaging device 1 according to the fifth embodiment of the presenttechnology. The imaging device 1 of FIG. 23 is different from theimaging device 1 described in conjunction with FIG. 1 in that acorrection unit 290 is further provided.

The correction unit 290 is used to correct an image signal generated bya pixel 110 arranged in a row where a failure of the control signaloccurs. The correction unit 290 specifies the failed row on the basis ofthe failure information output from the failure detector 280 andperforms correction of the image signal. The correction of the imagesignal may be performed by interpolation of the image signal. Theinterpolation may be performed by creating a mean value of the imagesignals for the rows immediately preceding and following the failed row,for example. The correction unit 290 stores the image signals of therows immediately preceding and following the failed row in a line memoryand creates a mean value of the stored image signals, so that the meanvalue is output as an image signal of the failed row. As a result, it ispossible to reduce degradation of image quality in the image signal.

Other configurations of the imaging device 1 are similar to those of theimaging device 1 of the first embodiment of the present technology, andthey will not be described repeatedly.

In this manner, according to the fifth embodiment of the presenttechnology, it is possible to reduce degradation of image quality of thepixel signal by performing correction of the image signal for the rowwhere a failure of the control signal occurs.

6. Sixth Embodiment

In the first embodiment described above, the same test voltage isapplied to the test signal generators 120 or the like. In contrast,different test voltages may also be applied to each row. The sixthembodiment of the present technology is different from the firstembodiment described above in that test signals having differentvoltages are generated in each row by applying different test voltagesto each row.

Configuration of Pixel Array Unit 10

FIG. 24 is a diagram illustrating an exemplary configuration of thepixel array unit 10 according to the sixth embodiment of the presenttechnology. The pixel array unit 10 of FIG. 24 is different from thepixel array unit 10 described in conjunction with FIG. 1 in that aplurality of resistors 140 are further provided.

The resistor 140 is used to divide the test voltage output from the testvoltage generator 240. The resistor 140 is arranged between the signalline 22 of the pixel array unit 10 and the ground in each row to dividethe test voltage to each row. The divided test voltage is applied to thetest signal generators 120 and 130 of each row. The test signalgenerator 120 or the like generates and outputs a test signal having avoltage corresponding to the applied test signal. Note that, in thepixel array unit 10 of FIG. 24, the resistor 140 is also arrangedbetween the test signal generators 120 and 130. As a result, it ispossible to apply different test voltages to the test signal generators120 and 130.

Configuration of Failure Detector

FIG. 25 is a diagram illustrating an exemplary configuration of thefailure detector 280 according to the sixth embodiment of the presenttechnology. The failure detector 280 of FIG. 25 is different from thefailure detector 280 described in conjunction with FIG. 7 in that a testsignal converter 288 is further provided. In addition, the failuredetector 280 of FIG. 25 is provided with a failure information generator289 instead of the failure information generator 284.

The test signal converter 288 converts the test signal output from thetest signal generator 120 or the like into information on the row. Thetest signal converter 288 has a table where the test voltages divided bythe pixel array unit 10 are stored, so that a row in which the testsignal generator 120 or the like that generates the test signal isarranged is specified by comparing the stored test voltage and the inputtest voltage. The test signal converter 288 outputs an identificationnumber of the specified row to the failure information generator 289 asthe information on the row. As a result, it is possible to easilyspecify the failed row.

The failure information generator 289 specifies the failed row on thebasis of the information on the row output from the test signalconverter 288 and generates failure information.

Other configurations of the imaging device 1 are similar to those of theimaging device 1 of the first embodiment of the present technology, andthey will not be described repeatedly.

In this manner, according to the sixth embodiment of the presenttechnology, the failed row is specified by generating the test signalshaving different voltages for each row by supplying different testvoltages for each row to the test signal generator 120 or the like. As aresult, it is possible to simplify the configuration of the imagingdevice 1.

7. Seventh Embodiment

In the first embodiment described above, the test signal is generated bythe test signal generator 120 or the like. In contrast, pixels 110 thatgenerate the test signals and the image signals may arranged, and afailure of the control signal line in the pixel may be detected. Theseventh embodiment of the present technology is different from the firstembodiment described above in that the test signal generator 120 or thelike is omitted.

Configuration of Pixel

FIG. 26 is a diagram illustrating an exemplary configuration of thepixel 110 according to the seventh embodiment of the present technology.The pixel 110 of FIG. 26 is different from the pixel 110 described inconjunction with FIG. 2 in that a diagnosis unit 117 is additionallyprovided. In addition, the signal line 22 is wired to the pixel 110 ofFIG. 26 to supply the test voltage. Furthermore, a diagnosis controlsignal line EN (Enable) that transmits the control signal to thediagnosis unit 117 is further arranged in the signal line 21. AnN-channel MOS transistor may be employed in the diagnosis unit 117. Notethat the test voltage generator 240 and the failure detector 280 areadditionally illustrated in FIG. 26 to show a relationship with thepixel 110.

The diagnosis unit 117 has a source connected to a cathode of thephotoelectric conversion element 111 and a gate connected to thediagnosis control signal line EN. A drain of the diagnosis unit 117 isconnected to the signal line 22. In addition, a drain of the resetelement 114 is also connected to the signal line 22.

The diagnosis unit 117 causes the pixel 110 to advance to a failuredetection mode. The diagnosis unit 117 applies the test voltage to thedrain of the electric charge transfer element 113 by electricallyconnecting the signal line 22 and the electric charge transfer element113. The diagnosis unit 117 may be electrically connected by inputtingthe ON signal from the diagnosis control signal line EN. Otherconfigurations of the pixel 110 are similar to those of the pixel 110described in conjunction with FIG. 2, and they will not be describedrepeatedly. Note that the electric charge transfer element 113 and thereset element 114 of FIG. 26 correspond to an example of the test signalgenerator described in the claims.

The vertical scanning units #1 (210) and #2 (220) according to theseventh embodiment of the present technology generate the control signalof the diagnosis unit 117 and output the control signal through thediagnosis control signal line EN. In addition, the test voltagegenerator 240 according to the seventh embodiment of the presenttechnology generates and outputs a reset voltage of the pixel 110 suchas the voltage supplied from the power line Vdd and the test voltage.

A failure in the control signal line according to the seventh embodimentof the present technology may be detected in the following manner.First, the vertical scanning units #1 (210) and #2 (220) output the ONsignal to the diagnosis control signal line EN. At the same time, thetest voltage generator 240 generates and outputs the test voltage. Then,the control signal is input to the transfer control signal line TR, thereset control signal line RST, and the pixel selection control signalline SEL, so that the test signal can be generated. Note that the testvoltage generator 240 generates and outputs the reset voltage in orderto generate a normal image signal from the pixel 110.

The pixel array unit 10 according to the seventh embodiment of thepresent technology is not necessarily provided with the test signalgenerator 120 or the like. For example, all of the pixels 110 of thepixel array unit 10 may have the configuration of the pixel 110 of FIG.26. In addition, for example, the pixels 110 arranged in both ends ofeach row out of the pixels 110 arranged in the pixel array unit 10 mayhave the configuration of the pixel 110 of FIG. 26.

Other configurations of the imaging device 1 are similar to those of theimaging device 1 of the first embodiment of the present technology, andthey will not be described repeatedly.

In this manner, according to the seventh embodiment of the presenttechnology, a failure in the control signal line is detected using thetypical pixel 110. Therefore, it is possible to omit the test signalgenerator and simplify the configuration of the pixel array unit 10.

Application to Mobile Object

The technologies according to this disclosure (present technology) areapplicable to various products. For example, the technologies accordingto this disclosure may be applied to a device mounted to any one ofmobile objects such as an automobile vehicle, an electric vehicle, ahybrid electric vehicle, a motorcycle, a bicycle, a personal mobility,an airplane, a drone, a ship, and a robot.

FIG. 27 is a block diagram schematically illustrating an exemplaryconfiguration of a vehicle control system as an example of a mobileobject control system according to a technology of this disclosure.

The vehicle control system 12000 has a plurality of electronic controlunits connected via a communication network 12001. In the example ofFIG. 27, the vehicle control system 12000 includes a driving systemcontrol unit 12010, a body system control unit 12020, a surroundinginformation detection unit 12030, an in-vehicle information detectionunit 12040, and a central control unit 12050. In addition, as functionalconfigurations of the central control unit 12050, a microcomputer 12051,a sound/image output element 12052, and an in-vehicle network I/F(interface) 12053 are illustrated.

The driving system control unit 12010 controls apparatuses relating to avehicle driving system on the basis of various programs. For example,the driving system control unit 12010 serves as a controller for adriving force generating apparatus for generating a driving force of avehicle such as an internal combustion engine or a driving motor, adriving force transmission mechanism for transmitting a driving force tothe wheels, a steering mechanism that adjusts a steering angle, abraking apparatus for generating a braking force of the vehicle, or thelike.

The body system control unit 12020 controls operations of variousapparatuses provided in a chassis on the basis of various programs. Forexample, the body system control unit 12020 serves as a controller for akeyless entry system, a smart key system, a power window device, orvarious lamps such as a head lamp, a back lamp, a brake lamp, a turnsignal lamp, or a fog lamp. In this case, radio waves transmitted from aportable device serving as a key or signals from various switches may beinput to the body system control unit 12020. The body system controlunit 12020 receives the input radio waves or signals and controls a doorlock device, a power window device, a lamp, and the like of the vehicle.

The surrounding information detection unit 12030 detects externalinformation on the vehicle where the vehicle control system 12000 ismounted. For example, the image sensing unit 12031 is connected to thesurrounding information detection unit 12030. The surroundinginformation detection unit 12030 allows the image sensing unit 12031 tophotograph an image around the vehicle and receives the photographedimage. The surrounding information detection unit 12030 may perform anobject detection process or a distance detection process for detecting apedestrian, a vehicle, an obstacle, a traffic control sign, or a trafficcontrol mark on a road surface on the basis of the received image.

The image sensing unit 12031 is an optical sensor that receives lightand outputs an electric signal depending on the amount of the receivedlight. The image sensing unit 12031 may output the electric signal as animage or distance information. In addition, the light received by theimage sensing unit 12031 may be visible light or non-visible light suchas infrared rays.

The in-vehicle information detection unit 12040 detects information onthe interior of the vehicle. For example, a driver's condition detectionunit 12041 that detects a drive's condition is connected to thein-vehicle information detection unit 12040. The driver's conditiondetection unit 12041 has, for example, a camera for photographing adriver, and the in-vehicle information detection unit 12040 maycalculate a driver's fatigue level or a mental concentration level ordetermine whether or not the driver is drowsy on the basis of thedetection information input from the driver's condition detection unit12041.

The microcomputer 12051 may compute a control target value for thedriving force generating apparatus, the steering mechanism, or thebraking device on the basis of in-vehicle information and/or surroundinginformation obtained from the surrounding information detection unit12030 or the in-vehicle information detection unit 12040 and output acontrol command to the driving system control unit 12010. For example,the microcomputer 12051 may perform a cooperated control forimplementing advanced driver assistance system (ADAS) features such ascollision avoidance or pre-crash, adaptive cruise control based on aninter-vehicle distance, intelligent speed adaptation, collision warning,or lane departure warning.

In addition, the microcomputer 12051 may perform a cooperated controlfor autonomous driving or the like to allow navigation without driver'sinput by controlling the driving force generating apparatus, thesteering mechanism, the braking device, or the like on the basis of thesurrounding information obtained from the surrounding informationdetection unit 12030 or the in-vehicle information detection unit 12040.

Furthermore, the microcomputer 12051 may output a control command to thebody system control unit 12020 on the basis of the surroundinginformation obtained from the surrounding information detection unit12030. For example, the microcomputer 12051 may perform a cooperatedcontrol for a glare-free capability such as switching between high-beamand low-beam by controlling head lamps depending on a position of thepreceding or oncoming vehicle detected by the surrounding informationdetection unit 12030.

The sound/image output element 12052 transmits an output signalcontaining at least one of sound and image data to an output devicecapable of visually or audibly notifying a vehicle passenger or theoutside of information. In the example of FIG. 27, the output deviceincludes, for example, an audio speaker 12061, a display unit 12062, andan instrument panel 12063. The display unit 12062 may include, forexample, at least one of an on-board display and a head-up display.

FIG. 28 is a diagram illustrating an example of the installationposition of the image sensing unit 12031. In FIG. 28, the image sensingunit 12031 includes the image sensing units 12101, 12102, 12103, 12104,and 12105.

The image sensing units 12101, 12102, 12103, 12104, and 12105 areprovided in, for example, a front nose, a side-view mirror, a rearbumper, a backdoor, and an upper part of an interior front glass, andthe like of the vehicle 12100. The image sensing unit 12101 provided inthe front nose and the image sensing unit 12105 provided in the upperpart of the interior front glass usually obtain front-view images of thevehicle 12100. The image sensing units 12102 and 12103 provided in theside-view mirrors usually obtain side-view images of the vehicle 12100.The image sensing unit 12104 provided in the rear bumper or the backdoorusually obtains rearview images of the vehicle 12100. The image sensingunit 12105 provided in the upper part of the interior front glassusually detects a preceding vehicle or pedestrian, an obstacle, asignal, a traffic control sign, lanes, or the like.

Note that FIG. 28 illustrates exemplary photosensory ranges of the imagesensing units 12101 to 12104. The photosensory range 12111 indicates aphotosensory range of the image sensing unit 12101 provided in the frontnose. The photosensory ranges 12112 and 12113 indicate photosensoryranges of the image sensing units 12102 and 12103 provided in theside-view mirrors. The photosensory range 12114 indicates a photosensoryrange of the image sensing unit 12104 provided in the rear bumper or thebackdoor. For example, a top bird's-eye view image of the vehicle 12100is obtained by combining the image data sensed by the image sensingunits 12101 to 12104.

At least one of the image sensing units 12101 to 12104 may have acapability of obtaining distance information. For example, at least oneof the image sensing units 12101 to 12104 may be a stereoscopic cameraprovided with a plurality of image sensors or an image sensor providedwith pixels for detecting a phase difference.

For example, the microcomputer 12051 may obtain distances to each solidobject within the photosensory ranges 12111 to 12114 and a temporalchange of the distance (a relative velocity against the vehicle 12100)on the basis of the distance information obtained from the image sensingunits 12101 to 12104 and extract, as a preceding vehicle, the closestone of the solid objects traveling at a predetermined velocity (forexample, 0 km/h or higher) in substantially the same direction as thatof the vehicle 12100 in the middle of a travel route of the vehicle12100. In addition, the microcomputer 12051 may set an inter-vehicledistance to be guaranteed relative to the preceding vehicle to performan automatic braking control (including an adaptive braking control), anautomatic acceleration control (including an adaptive speed control), orthe like. In this manner, the microcomputer 12051 may perform acooperated control for autonomous navigation or the like to allownavigation without driver's input.

For example, the microcomputer 12051 may extract solid object data onthe solid object on the basis of the distance information obtained fromthe image sensing units 12101 to 12104 by classifying the data into anauto-bicycle, a normal vehicle, a large-sized vehicle, a pedestrian,other solid objects such as a utility pole and the like and use thesolid object data in automatic obstacle avoidance. For example, themicrocomputer 12051 detects obstacles in the vicinity of the vehicle12100 dividingly into an obstacle recognizable and an obstacle notrecognizable by a driver of the vehicle 12100. In addition, themicrocomputer 12051 may determine a collision risk indicating a dangerlevel of collision with each obstacle and output a warning to a driverthrough an audio speaker 12061 or a display unit 12062 in a case wherethere is a possibility of the collision risk equal to or higher than asetting value. In addition, the microcomputer 12051 may perform forceddeceleration or avoidance steering using the driving system control unit12010 to provide driving assistance for collision avoidance.

At least one of the image sensing units 12101 to 12104 may be aninfrared camera capable of detecting infrared rays. For example, themicrocomputer 12051 may recognize a pedestrian by determining whether ornot there is a pedestrian in the images obtained from the image sensingunits 12101 to 12104. Such pedestrian recognition is performed by aprocess of extracting characteristic points from the images obtainedfrom the image sensing units 12101 to 12104 such as an infrared cameraand a process of performing a pattern matching processing for a seriesof characteristic points expressing a contour of the object to determinewhether or not the detected object is a pedestrian. If the microcomputer12051 determines that there is a pedestrian in the images obtained fromthe image sensing units 12101 to 12104 and recognizes a pedestrian, thesound/image output element 12052 controls the display unit 12062 suchthat a rectangular contour line for emphasizing the recognizedpedestrian is overlappingly displayed. In addition, the sound/imageoutput element 12052 may control the display unit 12062 such that anicon for indicating the pedestrian or the like is displayed in a desiredposition.

Hereinbefore, an exemplary vehicle control system applicable to thetechnology according to this disclosure has been described. Thetechnology according to this disclosure is applicable to the imagesensing unit 12031 out of the configurations described above.Specifically, the imaging device 1 of FIG. 1 is applicable to the imagesensing unit 12031. By applying the technology according to thisdisclosure to the image sensing unit 12031, it is possible to detect afailure in the control signal of the image sensor arranged in the imagesensing unit 12031.

Note that the aforementioned embodiments have been described to show anexample of how to implement the present technology, and the matters ofthe embodiments correspond to the matters of claims. Conversely, thematters of the claims are supported by the embodiments of the presenttechnology in which like names denote like elements. However, thepresent technology may be embodied in various forms without limiting tothose of the embodiments, and various modifications may be possiblewithout departing from the spirit and scope of the present technology.

In addition, the processing sequence described in the aforementionedembodiments may be understood on the basis of a method having such aseries of processes. Furthermore, the processing sequence may also beunderstood as a program for executing this series of processes or arecording medium storing the same. Such a recording medium may include,for example, a compact disc (CD), a mini-disc (MD), a digital versatiledisc (DVD), a memory card, a Blu-ray (registered trademark) disc, andthe like.

Note that the effects described herein are merely for exemplary purposesand are not be construed as being limitative. Other alternative effectsmay also be possible.

Note that the present technology may also include the followingconfigurations.

(1) An image sensor including:

an electric charge storing element configured to store transferredelectric charges;

a transfer control signal line configured to transmit a transfer controlsignal that controls a transfer of the electric charge generated inresponse to emitted light to the electric charge storing element;

a reset control signal line configured to transmit a reset controlsignal that controls a reset operation of the electric charge storingelement;

a test signal generator configured to generate a transfer test signal onthe basis of a test voltage for detecting a failure in the transfercontrol signal line and the reset control signal line and thetransmitted transfer control signal and generate a reset test signal onthe basis of the test voltage and the transmitted reset control signal;

a test voltage generator configured to supply a transfer test voltage tothe test signal generator as the test voltage when the transfer testsignal is generated and supply a reset test voltage to the test signalgenerator as the test voltage when the reset test signal is generated;and

a failure detector configured to detect a failure in the transfercontrol signal line and the reset control signal line on the basis ofthe generated transfer test signal and the generated reset test signal.

(2) The image sensor according to (1), in which the test voltagegenerator changes the test voltage supplied to the test signal generatorwhen the transfer test signal is generated from the transfer testvoltage to a voltage different from the transfer test voltage.

(3) The image sensor according to (1) or (2), in which the failuredetector detects a failure of the transfer control signal line in a casewhere the transfer test signal has a voltage different from the transfertest voltage.

(4) The image sensor according to (1) or (2), in which the failuredetector detects a failure of the transfer control signal line in a casewhere the reset test signal has a voltage different from the reset testvoltage.

(5) The image sensor according to (1) or (2), in which the failuredetector detects a failure of the reset control signal line in a casewhere the reset test signal has a voltage different from the reset testvoltage.

(6) The image sensor according to any of (1) to (5), in which the testvoltage generator supplies, as the transfer test voltage, a resetvoltage which is a voltage applied to the electric charge storingelement in the event of the reset operation.

(7) The image sensor according to any of (1) to (5), in which the testvoltage generator supplies, as the reset test voltage, a voltage rangingwithin a dynamic range of an image signal depending on the electriccharges stored in the electric charge storing element.

(8) The image sensor according to (1), in which the electric chargestoring element is arranged in a pixel, and

an image signal depending on the electric charges stored in the electriccharge storing element is generated from the pixel.

(9) The image sensor according to (8), in which the test signalgenerator has a capacitor configured to store the test voltage,

a signal generation element configured to generate an error signaldepending on the test voltage stored in the capacitor,

a transfer test signal generator configured to apply the test voltage tothe capacitor in response to the transfer control signal to allow thesignal generation element to generate the transfer test signal, and

a reset control signal generator configured to apply the test voltage tothe capacitor in response to the reset control signal to allow thesignal generation element to generate the reset test signal.

(10) The image sensor according to (8) or (9), further including a pixelselection control signal line configured to transmit, to the pixel, apixel selection control signal that controls output of the generatedimage signal from the pixel,

in which the test signal generator outputs the transfer test signal andthe reset test signal in response to the transmitted pixel selectioncontrol signal, and

the failure detector further detects a failure of the pixel selectioncontrol signal line on the basis of the output transfer test signal andthe output reset test signal.

(11) The image sensor according to (10), in which the failure detectordetects a failure of the pixel selection control signal line in a casewhere the transfer test signal has a voltage different from the transfertest voltage.

(12) The image sensor according to (10), in which the failure detectordetects a failure of the pixel selection control signal line in a casewhere the reset test signal has a voltage different from the reset testvoltage.

(13) The image sensor according to any of (8) to (12), further includinga control signal generator configured to generate the transfer controlsignal and the reset control signal and transmit the transfer controlsignal and the reset control signal through the transfer control signalline and the reset control signal line, respectively.

(14) The image sensor according to (13), in which the transfer controlsignal line has a signal line commonly connected to the control signalgenerator, the pixel, and the test signal generator in this order, and

the reset control signal line has a signal line commonly connected tothe control signal generator, the pixel, and the test signal generatorin this order.

(15) The image sensor according to (13), further including:

a second control signal generator configured to generate the transfercontrol signal and the reset control signal; and

a second test signal generator configured to generate the transfer testsignal and the reset test signal,

in which the transfer control signal line has a signal line commonlyconnected to the control signal generator, the test signal generator,the pixel, the second test signal generator, and the second controlsignal generator in this order, and

the reset control signal line has a signal line commonly connected tothe control signal generator, the test signal generator, the pixel, thesecond test signal generator, and the second control signal generator inthis order.

(16) The image sensor according to any of (9) to (15), in which thepixels are arranged in a matrix shape,

the test signal generator is arranged in each row,

the transfer control signal line is arranged each row to transmit thetransfer control signal to the pixel and the test signal generator,

the reset control signal line is arranged in each row to transmit thereset control signal to the pixel and the test signal generator, and

the failure detector detects a failure in a plurality of the transfercontrol signal lines and a plurality of the reset control signal lineson the basis of the transfer test signal output from a plurality of thetest signal generators and the reset test signal output from a pluralityof the test signal generators.

(17) The image sensor according to (16), further including a failureinformation generator configured to generate failure information asinformation on the failed row in which at least one of the transfercontrol signal lines and the reset control signal lines is failed on thebasis of a result of the detection of the failure detector.

(18) The image sensor according to (17), further including a correctionunit configured to correct the output image signal on the basis of thegenerated failure information.

(19) The image sensor according to any of (8) to (18), in which thecontrol signal generator is formed in a semiconductor chip differentfrom that in which the pixel and the test signal generator are formed,

the transfer control signal line transmits the transfer control signalbetween the different semiconductor chips through a connection terminal,and

the reset control signal line transmits the reset control signal betweenthe different semiconductor chips through a connection terminal.

(20) An imaging device including:

an electric charge storing element configured to store a transferredelectric charge;

a transfer control signal line configured to transmit a transfer controlsignal that controls a transfer of the electric charges generated inresponse to emitted light to the electric charge storing element;

a reset control signal line configured to transmit, to the pixel, areset control signal that controls a reset operation of the electriccharge stored in the electric charge storing element;

a test signal generator configured to generate a transfer test signal onthe basis of a test voltage for detecting a failure in the transfercontrol signal line and the reset control signal line and thetransmitted transfer control signal and generate a reset test signal onthe basis of the test voltage and the transmitted reset control signal;

a test voltage generator configured to supply a transfer test voltage tothe test signal generator as the test voltage when the transfer testsignal is generated and supply a reset test voltage to the test signalgenerator as the test voltage when the reset test signal is generated;

a failure detector configured to detect a failure in the transfercontrol signal line and the reset control signal line on the basis ofthe generated transfer test signal and the generated reset test signal;and

a processing circuit configured to process an image signal generateddepending on the electric charge stored in the electric charge storingelement.

(21) An imaging device comprising:

a first pixel comprising:

a first transfer transistor, wherein a first terminal of the firsttransfer transistor is coupled to a reference signal generation circuit;

a first reset transistor, wherein a first terminal of the first resettransistor is coupled to the reference signal generation circuit;

a first amplifier transistor, wherein a gate of the first amplifiertransistor is coupled to a second terminal of the first reset transistorand a second terminal of the first transfer transistor; and

a first select transistor coupled to the first amplifier transistor; and

a second pixel comprising:

a first photoelectric conversion element;

a second transfer transistor coupled to the first photoelectricconversion element;

a second reset transistor configured to receive a first predeterminedvoltage;

a second amplifier transistor coupled to the second transfer transistorand the second reset transistor; and

a second select transistor coupled to the second amplifier transistor.

(22) The imaging device according to (21), wherein the first pixelfurther comprises an electric charge storing element coupled to thesecond terminal of the first transfer transistor.

(23) The imaging device according to (21) or (22), wherein the secondpixel further comprises an electric charge storing element coupled tothe second transfer transistor.

(24) The imaging device according to (23), wherein the second transfertransistor has a first terminal coupled to the first photoelectricconversion element, a second terminal coupled to the electric chargestoring element, and a gate configured to receive a transfer enablingsignal.

(25) The imaging device according to any of (21)-(24), wherein thereference signal generation circuit is configured to provide the firstpixel with a first voltage and a second voltage different from the firstvoltage.

(26) The imaging device according to (25), wherein the first transfertransistor is configured to transfer the first voltage to the firstamplifier transistor and the first reset transistor is configured totransfer the second voltage to the first amplifier transistor.

(27) The imaging device according to any of (21)-(26), furthercomprising a failure detector coupled to an output terminal of the firstselect transistor, the failure detector comprising at least onecomparison element.

(28) The imaging device according to (27), wherein the failure detectoris disposed on a first chip and the first pixel is disposed on a secondchip, and wherein the failure detector is coupled to the output terminalof the first select transistor via an inter-chip connection terminal.

(29) The imaging device according to (27), wherein the failure detectoris coupled to the output terminal of the first select transistor via ananalog-to-digital conversion element.

(30) The imaging device according to (29), wherein the at least onecomparison element is configured to compare a signal provided by theanalog-to-digital conversion element with a signal provided by a testvoltage storing element.

(31) The imaging device according to any of (21)-(30), wherein thesecond pixel further comprises a first diagnosis transistor coupled tothe first photoelectric conversion element and the second transfertransistor.

(32) The imaging device according to any of (21)-(31), wherein the firstpixel further comprises a second diagnosis transistor and a secondphotoelectric conversion element, wherein the second diagnosistransistor is coupled to the second photoelectric conversion element andthe first transfer transistor.

(33) The imaging device according to (32), wherein the first terminal ofthe first transfer transistor is coupled to the reference signalgeneration circuit via the second diagnosis transistor.

(34) The imaging device according to any of (21)-(33), wherein, when thefirst reset transistor is enabled, an electric charge storing element isreset.

(35) The imaging device according to any of (21)-(34), wherein thesecond transfer transistor has a first terminal coupled to the firstphotoelectric conversion element.

(36) The imaging device according to (35), wherein the second transfertransistor has a second terminal coupled to a gate of the secondamplifier transistor and a gate configured to receive a transferenabling signal.

(37) The imaging device according to (36), wherein the gate of thesecond amplifier transistor is configured to receive a signal from thesecond transfer transistor based on an electric charge generated by thephotoelectric conversion element.

(38) The imaging device according to any of (21)-(37), wherein the firstpixel and the second pixel are part of a same pixel row, and wherein agate of the first transfer transistor is coupled to a gate of the secondtransfer transistor.

(39) The imaging device according to any of (21)-(38), wherein at leastone among the first transfer transistor, the first select transistor,the first reset transistor and the first amplifier transistor is an NMOStransistor.

REFERENCE SIGNS LIST

-   -   1 Imaging device    -   10 Pixel array unit    -   11 Signal line    -   20 Driving unit    -   21 Signal line    -   110 Pixel    -   111 Photoelectric conversion element    -   112 Electric charge storing element    -   113 Electric charge transfer element    -   114 Reset element    -   115 Signal generation element    -   116 Signal output element    -   117 Diagnosis unit    -   120, 130 Test signal generator    -   140 Resistor    -   160 Connection terminal    -   210, 220 Vertical scanning unit    -   211 Address decoder    -   212 Pixel driving unit    -   230 A/D conversion unit    -   231 A/D conversion element    -   232 Constant current power source    -   233 Selector    -   240 Test voltage generator    -   250 Reference signal generator    -   260 Control unit    -   270 Signal processing unit    -   280 Failure detector    -   281 Test voltage storing element    -   284 Failure information generator    -   285 Signal shaping element    -   286 Encoder    -   287, 289 Failure information generator    -   288 Test signal converter    -   290 Correction unit    -   410 Pixel unit    -   420 Failure detection unit    -   12031 Image sensing unit

The invention claimed is:
 1. An imaging device comprising: a first pixelcomprising: a first transfer transistor, wherein a first terminal of thefirst transfer transistor is coupled to a test voltage generator and asecond terminal of the first transfer transistor is coupled to atransfer control signal line from a vertical scanning unit; a firstreset transistor, wherein a first terminal of the first reset transistoris coupled to the test voltage generator and a second terminal of thefirst reset transistor is coupled to a reset control signal line fromthe vertical scanning unit, wherein the first terminal of the firsttransfer transistor and the first terminal of the first reset transistorare configured to receive from the test voltage generator a transfertest voltage during a transfer signal test and a reset test voltage,different from the transfer test voltage, during a reset signal test; afirst amplifier transistor, wherein a gate of the first amplifiertransistor is directly coupled to a third terminal of the first resettransistor and is directly coupled to a third terminal of the firsttransfer transistor; and a first select transistor coupled to the firstamplifier transistor; and a second pixel comprising: a firstphotoelectric conversion element; a second transfer transistor having afirst terminal coupled to the first photoelectric conversion element; asecond reset transistor configured to receive a first predeterminedvoltage; a second amplifier transistor coupled to the second transfertransistor and the second reset transistor; and a second selecttransistor coupled to the second amplifier transistor.
 2. The imagingdevice according to claim 1, wherein the first pixel further comprisesan electric charge storing element coupled to the third terminal of thefirst transfer transistor.
 3. The imaging device according to claim 1,wherein the second pixel further comprises an electric charge storingelement coupled to the second transfer transistor.
 4. The imaging deviceaccording to claim 3, wherein the second transfer transistor has asecond terminal coupled to the electric charge storing element, and agate configured to receive a transfer enabling signal on the transfercontrol signal line.
 5. The imaging device according to claim 1, whereinthe test voltage generator is configured to provide the first pixel witha first voltage and a second voltage different from the first voltage.6. The imaging device according to claim 5, wherein the first transfertransistor is configured to transfer the first voltage to the firstamplifier transistor and the first reset transistor is configured totransfer the second voltage to the first amplifier transistor.
 7. Theimaging device according to claim 1, further comprising a failuredetector coupled to an output terminal of the first select transistor,the failure detector comprising at least one comparison element.
 8. Theimaging device according to claim 7, wherein the failure detector isdisposed on a first chip and the first pixel is disposed on a secondchip, and wherein the failure detector is coupled to the output terminalof the first select transistor via an inter-chip connection terminal. 9.The imaging device according to claim 7, wherein the failure detector iscoupled to the output terminal of the first select transistor via ananalog-to-digital conversion element.
 10. The imaging device accordingto claim 9, wherein the at least one comparison element is configured tocompare a signal provided by the analog-to-digital conversion elementwith a signal provided by a test voltage storing element.
 11. Theimaging device according to claim 1, wherein, when the first resettransistor is enabled, an electric charge storing element is reset. 12.The imaging device according to claim 1, wherein the second transfertransistor has a second terminal coupled to a gate of the secondamplifier transistor and a gate configured to receive a transferenabling signal on the transfer control signal line.
 13. The imagingdevice according to claim 12, wherein the gate of the second amplifiertransistor is configured to receive a signal from the second transfertransistor based on an electric charge generated by the photoelectricconversion element.
 14. The imaging device according to claim 1, whereinthe first pixel and the second pixel are part of a same pixel row, andwherein a gate of the first transfer transistor is coupled to a gate ofthe second transfer transistor.
 15. The imaging device according toclaim 1, wherein at least one among the first transfer transistor, thefirst select transistor, the first reset transistor and the firstamplifier transistor is an NMOS transistor.